Single handle faucets, commonly referred to as mixing valves, that control the flow of both hot and cold water have seen vast consumer acceptance. The faucets are commonly constructed such that a handle or knob is movable in two distinct directions to adjust the mix of hot and cold water and to adjust the volume rate, i.e. flow.
The two basic types of mixing valves that have seen wide commercial acceptance are plate valves and ball valves. Ball valves are renowned for reliable and durable one piece valve construction that is easily assembled and easily repaired. Plate valves on the other hand offer a drive mechanism that allows motion of the handle in two distinct directions that has found widest commercial acceptance. This desirable handle motion allows for an orbiting motion of the handle about a fixed axis of the valve body and a rocking, i.e. pivoting motion about a axis that moves with respect to the valve housing as the handle orbits about the fixed axis. The moving axis is substantially perpendicular to the fixed axis of the valve housing. A characteristic of this type of handle motion is that when the handle is rocked to an off position, the mix ratio of hot and cold water can be remembered by the angular location of the handle about the fixed axis so that when the faucet is turned back on, one has the option of obtaining the same mix of hot and cold water flows through the faucet regardless of the flow amount. The fixed axis is most commonly found to be vertically oriented.
Recently, ball valves have been devised that allow the handle to be operated in the same fashion as the above described plate type mixing valves. The ball valve is disclosed in U.S. Pat. No. 4,449,551 issued to Lorch on May 22, 1984. Another system is disclosed in PCT application PCT/US91/07816 filed on Oct. 22, 1991 by the present applicant and the disclosed structure and operation is incorporated herein by reference.
There are also commercially available faucets which incorporate devices that prevent the faucet from either being adjusted to provide excessively hot mixture of water for reasons of economy, safety, or conservation of heating fuel. Furthermore, devices have also been incorporated to prevent excessive flow for reasons of economy or conservation of water.
Known devices intended to impede or obstruct motion exceeding a certain limit can be classified into four types. In the first type of device, there is a restrictor that is fixedly mounted in the flow passage to choke or restrict the flow of water therethrough. This type of device precludes the ability to obtain a flow rate that is greater than the imposed limit of the restrictor without physical disassembly of either the faucet or piping upstream from the faucet.
The second type of device includes a stop built into the faucet such as a stop shoulder in the form of a lobe or screw that provides a stop limit in the faucet. If the maximum capacity can be adjusted as in the case of the screw, the faucet handle needs to be disassembled to reach access to the adjustment screw. These first two classes of flow restrictors tend to positively impede the user from overriding the imposed limit. Any adjustment to the stop limit is infrequently done and is usually done to permanently change the stop position of the faucet.
Two other classes of restrictors provide for a convenient override of the preset limit which only dissuades the user from obtaining adjustment above a predetermined limit. The third class of restrictors has a limit stop which has a push button that when pressed allows the handle to operate beyond the predetermined limit. In normal use, the operator normally operates the faucet normally below the predetermined limit without pressing the button, but upon occasion can push the button to allow the faucet to be adjusted beyond the predetermined limit. The disadvantage of this class of flow restriction is the expense in the complex construction and the consequent high cost. Furthermore, the push button must be manually pushed each time the faucet is adjusted beyond the preset limit. The action of pushing the button can be inconvenient because it is obtained by different movement or actions than the movement or actions that control adjustment of the flow and temperature mix of the mixing valve.
The fourth class of flow restrictor is a spring type device which repels the control member when the control member is opened beyond the closed position. During operation of a valve with this type of flow restrictor, the control member is manually moved and held in place against the biasing force of a spring. Upon release of the handle, the handle is resiliently moved back to a position such as the closed position by the biasing force of the spring acting against the opening action of the valve. The inconvenience in this type of device is that the operator must manually keep the handle pressed beyond the preset position the entire time the increased flow rate is desired. Devices of this type are often incorporated to provide automatically closing faucets.
Modern single handle mixing valves have been developed with easier and more consistent operating parameters. The mixing valve can be quickly operated from a closed position to an open position and quickly moved in the opposite fashion, from a full open position to a closed or off position. Furthermore, the operating force needed to operate modern faucets is substantially constant throughout the full operating range of the valve either during adjustment of the flow or temperature mix.
Usually, the force needed is low to allow ease of operation of the faucet controls. For example, children and physically handicapped people require smooth operating faucets. Furthermore, a smoothly operating faucet is a commercial necessity. One drawback arises from the low operating forces that provide ease of control of modern faucets. The small operating force allows for quick movement of the control stem. Quick movement from the open to the fully closed position can lead to an abrupt cessation of flow of water and thus lead to the undesirable symptom often referred to as hammer knock.
Anti-knock devices have been incorporated in pipe lines for water flow. These often are in the form of an extra dead end head section joined to the normal pipe leading to the mixing faucet. The dead end pipe section is filled with air that compresses when flow is abruptly stopped in the pipe. However, not all piping incorporates the extra head section.
What is need is a flow restrictor device which provides for a preset flow capacity but allows for an easily operated override of the preset amount when desired without introducing different actions or motions that are used to adjust the flow or temperature mix of the mixing valve and simultaneously provides for limiting the speed with which the flow is ceased in the pipe so as to prevent hammer knock. What is also needed is a faucet that has a mechanism that provides for greater minimum operating force for a predetermined part of the range of the faucet valve operation.